Speedometer-magnet drive



OQB. HJORTH. SPEEDOMETER MAGNET DRIVE.

APPLICATION FILED FEB. I8, 1918.

1,335,833. Patented Apr- 6-, 1920.

I To all whom it may concern:

UNITED STATES PATE T" OFFICE.

OSCAR B. HJ'ORTH, OF CHICAGO, ILLINOIS, ASSIGNOR T STEWART-WARNER SPEED-OMETER CORPORATION, OF CHICAGO, ILLINOIS, A CORPORATION OF VIRGINIA.

SPEEDOMETERFMQG'NET IJRIVE.

Specification of Letters Patent. I

Application filed February 1a; 1918. Serial No. 217.777.

Be it known that I, OsoAR B. HJORTH, a

citizen of the United States, residing at Chicago, in the county of Cookand the State of Illinois, have invented certain new and usefulImprovements in Speedometer-Magnet Drives, of which the followmg IS aspeci- .fi-cation, reference being had'to the accompanying drawings,forming a partthereof. 7 The purpose of this invention is to provide anoiseless form of drive connection for transmitting the continuousrotation of a drive shaft to a rotary magnet or other metering elementwithin a speedometer casing, particularly when such shaft and meter ingelements are journaled upon relatively transverse or oblique axes. Theinvention consists in the details of construction and arrangementhereinafter described -and shown in the drawings as indicated by theclaim.

In the drawings:

Figure 1 is an axial vertical section of a speedometer including a driveconnection embodying this invention.

Fig. 2 is an enlarged detail view taken as a section at line 22 on Fig.1 and showing particularly the parts embodying the novel driveconnection.

Fig. 3 is a detail section taken as indicated at line 33 on Fig. 2.

Referring first to Fig. 1,-it will be seen that the instrument comprisesa casing, 1,

-which is entered at the back by a drive shaft, 2, in a journal bearing,3. Within the casing a magnet, 4, of substantially circular outline isshown secured to a carrier, 5, on a shaft,- 6, journaled in a bearing,7.

supported within the casing, 1, while the usual non-magnetic dragelement appearsin the form of an inverted -cup:shaped member, 8, havingits flange, or skirt, overhanging the magnet, 4, in position to reglsterat window 9,, of dial plate, 10, it being un-.

derstood that said skirt of the member, 8, carries a scale and speedindicating numerals, not shown.

In the particular instrument illustrated, the shaft, 2, is disposed uponan axis oblique to the axis of the magnet'shaft, 6, and in suchcasesit'has been the practice heretofore to transmit the rotation of theshaft, 2, to the magnet, through the medium of bevel I I I I gears; butas 1s well understood, 1t'1s quite difficult to adjust such gears andmaintain them in adjustment so perfect that they will not causeconsiderable noise, especially if the speed of rotation of the shaft, 2,is rather high. Such noise is of course objectionable, and also is asymptom of undesirable friction and 'wear in the parts.

Patented A r. 6, 1920.

A much quieter form of transmission has therefore been devised,embodying a torsion link, composed of a pair of flat bars, 11,permanently assembled in parallel relation and connected by "a'spacer,12, having reducedv end portions,-13, which are riveted over afterpassing through apertures respectively at about the middle of the lengthof each of the bars, 11. Between the bars, 11, at each end, there iscarried the block or cross, 14, of a universal joint, having trunnions,15, engaged in apertures of the bars, 11, and havingtransversely-disposed trunnions, 16, pivotally carried in the arms offorks, 17, and 18, which are secured respectively to adjacent ends ofshaft, 2, and shaft, 6. As shown, the forks, 17 and 18, may be formed ofsheet metal drawn into the shape of the cup with the opposite sidespartly cut away leaving standlng the two portions which form the forksbetween which-the members, 14, are carried. The bottoms of suchcup-shaped members, 17 and 18 are apertured and secured to the reducedend portion of the shaft, 2, or 6, as the case'may be, by rivetingoverof such reduced portion. As indicated further in Fig. 2, the shaft,6, is made hollow for thepurpose of accommodating a step jewel bearing,19, for the spindle, 20, of the oscillatory drag member, 8.

It will be evident that the torsion link ranged with its axis at anangle to that of 106 said member, a torsion link composed of twoparallel side bars and a spacer connecting torsion link to said memberand drive shaft them intermediate their ends; forked termirespectively.

nals on the adjacent parts of said member In testimony whereof I havehereunto set 10 and shaft respectively, and connector blocks my hand atChicago, Illinois, this 9th day trnnnioned in each of said forks and inof February, 1918. the respective ends of said side bars, constitutinguniversal joint connections for the DSCAR B. HJORTH,

